KR101614325B1 - Method of manufacturing silicon carbide powder contaning vanadium and silicon carbide single cryctal thereof - Google Patents

Abstract

The present invention relates to a preparation method of silicon carbide powder, which prepares a silicon carbide precursor having a uniform Si-O-V network and prepares silicon carbide powder with uniformly doped vanadium in the lattice of the silicon carbide precursor through a carbothermal reduction reaction, and to silicon carbide powder for growing silicon carbide crystals having high resistance prepared thereby.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a vanadium-containing silicon carbide powder and a method for manufacturing the same,

More particularly, the present invention relates to a method for producing vanadium-containing silicon carbide powder having a high yield by uniformly reacting carbon and silica uniformly doped with vanadium by a thermal carbon reduction reaction. And a high resistance silicon carbide single crystal produced by the method.

Representative methods for producing silicon carbide powder include Acheson method, carbothermal reduction method, synthesis method using gas phase reaction, liquid phase polymer reaction method, and the like. Among them, the Acheson method is a representative industrial production method suitable for producing alpha-phase silicon carbide (α-SiC), which is made of quartz and coke as starting materials and is made of silicon carbide at a temperature of 2,000-2,400 ° C. .

On the other hand, the thermal carbon reduction method, the gas phase reaction method, and the liquid phase polymer reaction method are suitable for producing beta-phase silicon carbide (β-SiC) stable in a low temperature range, but they are disadvantageous in mass production except for the thermal carbon reduction method . The thermal carbon reduction method is a method of producing silicon carbide by mixing silica and carbon at a certain ratio and then performing heat treatment in an inert gas atmosphere. The thermal carbon reduction method can obtain a high-purity powder having a uniform particle size, and can produce silicon carbide excellent in sintered body characteristics.

The carbothermal reduction method is a method of producing silicon carbide by heat-treating silica mixed with carbon in an argon atmosphere. During the heat treatment, silica reacts with carbon, and oxygen in silica is formed as carbon monoxide (CO) gas, The remaining silicon reacts with carbon to form silicon carbide. The reaction formula is as follows.

_{SiO 2 + 3C → SiC + 2CO} ↑ [ Equation 1]

The details are as follows. (s: solid, g: gas)

SiO ₂ (s) + C (s)? SiO (g) + CO (g)

SiO2 (g) + 2C (s) SiC (s) + CO (g)

SiO 2 produced as an intermediate is in a gaseous state and the rate of sublimation of the SiO 2 gas is higher than that of the reaction gas, resulting in a low yield of silicon carbide produced due to the loss of silicon.

In order to solve the above problems, Korean Patent Laid-Open No. 10-2013-0106653 discloses a method for producing silicon carbide powder with improved yield by a thermal carbon reduction method.

On the other hand, silicon carbide (SiC) single crystals are very stable in terms of thermal and chemical properties, have excellent mechanical strength, and have excellent properties such as high dielectric breakdown voltage and high thermal conductivity as compared with silicon, and they are attracting attention as a next-generation semiconductor material. The field of electronic devices using silicon carbide single crystals is largely divided into an LED and a power device field which are doped with nitrogen and used in the form of a conductive substrate, and an RF communication device section using a silicon carbide single crystal having properties such as a vanadium- have.

Examples of the method for producing the silicon carbide single crystal include a physical vapor transport method (PVT method), a top seeded solution growth method (TSSG method), a high temperature chemical vapor deposition method (HTCVD method) ), Among which the sublimation method is the most commercially available.

In the single crystal growth method using the sublimation method, a seed is attached to the top of the crucible, and the silicon carbide powder is used as a raw material to sublimate at a temperature of 2200 ° C. or higher and then recrystallized to a relatively low temperature seed surface to grow a single crystal Silicon carbide powder with high purity and large particle size is used as raw material.

As described above, a silicon carbide single crystal having the same characteristics as a high-resistance insulator is used in the RF communication element part, and vanadium-doped silicon carbide single crystal is widely used for this purpose. In order to obtain vanadium-doped high-resistance silicon carbide single crystal, silicon carbide powder and vanadium metal powder are generally mixed as raw materials. In this case, the vanadium sublimation speed is high at high temperature, But it is disadvantageous in that it varies significantly depending on the location.

Accordingly, it is necessary to prepare a silicon carbide single crystal having vanadium uniformly distributed in the entire region. To this end, a method for manufacturing a silicon carbide powder uniformly applied to a vanadium diagonal lattice, which is used as a raw material for single crystal growth, It is a matter of urgency.

Accordingly, a problem to be solved by the present invention is to prepare a silicon carbide precursor having a uniform Si-O-V network as a raw material for a high resistance silicon carbide single crystal and then uniformly doping the vanadium into the lattice through a conventionally known hot carbon reduction method And a method for producing the silicon carbide powder.

Also, the present invention provides a vanadium-containing silicon carbide powder produced by the above-described method.

Also, a vanadium-containing high resistance silicon carbide single crystal in which vanadium is uniformly distributed in a single crystal produced by using the vanadium-containing silicon carbide powder is provided.

In order to solve the above problems,

(a) preparing a vanadium-containing silica powder by sol-gel reaction of a reaction mixture represented by the following formula (1);

(b) mixing the vanadium-containing silica powder and carbon to produce a silicon carbide precursor; And

(c) subjecting the silicon carbide precursor thus prepared to heat treatment at 1400-2200 ° C under vacuum or a gas atmosphere selected from helium, neon, and argon; and a process for producing vanadium-containing silicon carbide powder,

[Chemical Formula 1]

In the above formula (1)

R is an alkyl group having 5 to 20 carbon atoms or a phenyl group.

According to an embodiment of the present invention, the reaction mixture of Formula 1 is synthesized by mixing a silica starting material and a vanadium starting material. The silica starting material may be a silicon alkoxide, a siloxane-based polymer, And an oxane-based polymer, and the vanadium starting material may be at least one selected from vanadium alkoxide, vanadium acetylacetonate, and vanadium oxychloride.

According to another embodiment of the present invention, the vanadium content of the vanadium-containing silica powder may be 1-5 wt%.

According to another embodiment of the present invention, the silicon carbide precursor may be prepared by further mixing at least one selected from the group consisting of carbon black, graphite, pitch, phenolic resin, and polystyrene resin in step (b) .

According to another embodiment of the present invention, the heat treatment step (c) includes: a first heat treatment step of carbonizing the silicon carbide precursor at 1400 to 1600 ° C; And a second heat treatment step of inducing crystallization at 1800-1900 ° C after the first heat treatment.

According to another embodiment of the present invention, the first heat treatment step may start the carbonation reduction reaction at 1400-1600 ° C and may be maintained for 5-7 hours.

Also, the second heat treatment step may induce crystallization at 1800-1900 ° C for 2-3 hours to obtain a highly crystalline silicon carbide powder.

According to another embodiment of the present invention, the silicon carbide precursor produced in step (b) may be calcined at a temperature of 600-1000 ° C in a vacuum or in a gas atmosphere selected from helium, neon and argon before the step (c) Step;

According to another embodiment of the present invention, the step (c) may further include a step of performing a decarburization process at 600 to 1000 ° C in an atmospheric environment.

Further, in order to solve the above problems,

Wherein the silicon carbide has a purity of 99.0-99.9% in a beta phase crystal phase and an average particle size of the vanadium-containing silicon carbide powder is 1-100 [mu] m. The vanadium-containing silicon carbide powder according to the above- Containing silicon carbide powder and a silicon carbide single crystal produced using the same.

According to the present invention, it is possible to manufacture a silicon carbide powder in which vanadium is uniformly distributed in a silicon carbide lattice, and a high-resistance silicon carbide single crystal having a resistance higher than 10 ³ ohm-cm It is possible to obtain.

1 is a result of X-ray diffraction analysis of the silicon carbide powder produced according to Example 1 of the present invention.
2 is an electron microscope image of silicon carbide powder prepared according to Example 1 of the present invention.
FIG. 3 is a result of X-ray diffraction analysis of the silicon carbide powder produced according to Example 2 of the present invention.
4 is an electron microscope image of silicon carbide powder produced according to Example 2 of the present invention.
5 is a result of X-ray diffraction analysis of the silicon carbide powder produced according to Comparative Example 1 of the present invention.
6 is an electron micrograph of the silicon carbide powder produced according to Comparative Example 1 of the present invention.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a method for producing a silicon carbide precursor having a uniform Si-O-V network and a vanadium-containing silicon carbide powder which is uniformly doped in the vanadium diaphragm through a thermal carbon reduction reaction of the silicon carbide precursor , Characterized by comprising the following steps.

(a) preparing a vanadium-containing silica powder by sol-gel reaction of the reaction mixture represented by the following formula (1)

(b) mixing the produced vanadium-containing silica powder with carbon to prepare a silicon carbide precursor, and

(c) heat treating the prepared silicon carbide precursor at 1400-2200 DEG C under vacuum or a gas atmosphere selected from helium, neon and argon,

[Chemical Formula 1]

In the above formula (1)

R is an alkyl group having 5 to 20 carbon atoms or a phenyl group.

First, in step (a), the reaction mixture represented by Formula 1 is subjected to a sol-gel reaction to produce a vanadium-containing silica powder having a uniform Si-OV network. The reaction mixture contains silica- Materials are mixed and synthesized. At this time, examples of the silica starting material include silicon alkoxide such as tetraethyl orthosilicate (TEOS) and tetramethyl orthosilicate (TMOS), siloxane polymer such as polydimethyl siloxane (PDMS), and silsesquioxane polymer such as polyhedral oligomeric silsesquioxane (POSS) It is preferable to use at least one selected from vanadium alkoxide, vanadium acetylacetonate, and vanadium oxychloride as the vanadium starting material.

The vanadium content of the vanadium-containing silica powder prepared through the above reaction is preferably 1-5 wt%. If it is less than the lower limit, the vanadium content is low, and the present invention is insufficient for use as a raw material of the desired vanadium-containing silicon carbide single crystal. If the vanadium content is above the upper limit, the amount exceeds the amount that can be contained in the silicon carbide lattice, There is a problem that the crystal quality is deteriorated when the silicon carbide powder is produced.

Next, in the step (b), the vanadium-containing silica powder prepared in the step (a) is mixed with carbon to prepare a silicon carbide precursor. When the vanadium-containing silica powder is mixed with carbon, the silicon carbide precursor may be prepared by further mixing at least one selected from carbon black, graphite, pitch, phenolic resin, and polystyrene resin.

Next, in the step (c), the silicon carbide precursor prepared in the step (b) is heat-treated at 1400-2200 ° C in a vacuum or a gas atmosphere selected from helium, neon and argon to obtain vanadium-containing silicon carbide powder. The heat treatment step may include a first heat treatment step of carbonizing the silicon carbide precursor at 1400-1600 ° C, and a second heat treatment step of inducing crystallization at 1800-1900 ° C after the first heat treatment.

Generally, in order to prepare the beta-phase silicon carbide powder by the thermal carbon reduction method, the silicon carbide precursor is generally reacted by heat treatment at 1600-1800 ° C. However, according to the thermal carbon reduction reaction, the reaction of [Formula 2-1] occurs explosively in the range of 1400-1600 ° C. At this time, since the reaction of [Formula 2-1] is faster than the reaction of [Formula 2-2], the loss of SiO gas is very large when the heat treatment is performed in the range of 1600-1800 ° C.

Therefore, it is necessary to maintain the reaction time in the range of 1400 to 1600 ° C, more preferably in the range of 1400 to 1550 ° C in order to minimize the loss of SiO gas.

However, the temperature may not sufficiently progress the reaction, and unreacted silica may remain. Therefore, since the unreacted silica is minimized and a reaction temperature of 1800 ° C or higher is required to obtain a highly crystalline powder, a second heat treatment step in the range of 1800-1900 ° C is required, whereby a high purity beta It is possible to obtain silicon carbide on the silicon substrate.

In the heat treatment step according to the present invention, the temperature of the first heat treatment step is preferably in the range of 1,400-1,600 ° C. Silicon carbide can be produced only by the first heat treatment step. However, since silicon carbide obtained in the first heat treatment step forms small particles having a size of less than 1 占 퐉, which is low in crystallinity, it is required to produce 1,800-1,900 占 폚 A step to complete the reaction in the range is required.

In the present invention, in order to produce a high-purity silicon carbide with high yield by using a silicon carbide precursor, the first and second heat treatment steps are performed as a basic process. However, the silicon carbide precursor prepared in the step (b) Followed by calcination at 600-1000 占 폚 under a gaseous atmosphere selected from helium, neon and argon.

The vanadium-containing silicon carbide powder produced after the second heat treatment step may be subjected to a decarburization treatment at 600-1000 ° C in an atmospheric environment after the step (c) to remove the remaining carbon to obtain high purity silicon carbide powder. The method comprising the steps of:

Using the above-described production method of the present invention, the vanadium-containing silicon carbide powder having a purity of the beta-phase crystal of 99.0-99.9%, the vanadium-containing silicon carbide powder having an average particle size of 1-100 [ Can be prepared.

Further, when the silicon carbide single crystal is grown by a generally known method under high temperature and high pressure by using the vanadium-containing silicon carbide powder, vanadium-containing high resistance silicon carbide single crystal having vanadium uniformly distributed in the single crystal can be produced.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments and the like. It will be apparent to those skilled in the art, however, that these examples are provided for further illustrating the present invention and that the scope of the present invention is not limited thereto.

Production Example 1. Preparation of 1 wt% vanadium-containing silica powder

Synthesis of Silica Powder As a starting material, TEOS (tetra-ethyl-ortho-silicate) and vanadium oxytripropoxide represented by the following formula 2 were used, and 60 ml of TEOS and 300 ml of vanadium oxytriproxide And 0.52 ml of sodium hydroxide were mixed to prepare a reaction mixture represented by the above formula (1). 200 ml of ethanol was added as a solvent and the reaction mixture was added and stirred. While maintaining the stirring, the temperature was gradually raised to 50 ° C. When the temperature was stably maintained, the pH was adjusted to 5% by adding ammonia solution 10. Ammonia was added to form a precipitate, which was reacted for at least 12 hours while stirring. The slurry, which had been reacted, was washed and centrifuged and then dried.

(2)

Production Example 2. Preparation of 5 wt% vanadium-containing silica powder

Was prepared in the same manner as in Preparation Example 1, except that 2.60 ml of vanadium oxytriproxide was used to prepare 5 wt% of vanadium-containing silica powder.

Production Example 3. Preparation of 10 wt% vanadium-containing silica powder

Vanadium oxytriproxide was prepared in the same manner as in Preparation Example 1, except that 5.20 ml of vanadium oxytriproxide was used to prepare 10 wt% vanadium-containing silica powder.

Example 1.

10 g of the vanadium-containing silica precursor synthesized in Preparation Example 1 was uniformly mixed with 4 g of carbon powder through a ball mill process, heated to 1400 ° C at a rate of temperature rise of 20 ° C per minute in an argon atmosphere, and maintained for 5 hours to prepare a silicon carbide powder And then heat-treated at 1800 ° C for 2 hours at a heating rate of 10 ° C per minute to produce a crystalline silicon carbide powder. The crystalline silicon carbide powder thus prepared was heat-treated at 600 ° C. for 6 hours in an air atmosphere to remove unreacted carbon to obtain a high-purity vanadium-containing silicon carbide powder.

The formation of silicon carbide was confirmed by X-ray diffractometer, and it was confirmed that all the peaks match with the silicon carbide peak (FIG. 1). In the case of silicon carbide, X-ray diffraction peaks were clearly observed at positions 35.7, 41.4, and 60 °, indicating that the particles were formed in the β phase (JCPDS No. 74-2307). The shape of the particles was confirmed by a scanning electron microscope and the hexagonal crystals were found to be excellent in single phase (FIG. 2). The chemical composition of the silicon carbide powder was found to be 0.95 wt% based on the Korean Industrial Standard (KS L1612).

Example 2.

10 g of the vanadium-containing silica precursor synthesized in Preparation Example 2 was uniformly mixed with 4 g of carbon powder through a ball mill process, heated to 1400 ° C at a rate of 20 ° C / min under an argon atmosphere, and maintained for 5 hours to prepare a silicon carbide powder And then heat-treated at 1800 ° C for 2 hours at a heating rate of 10 ° C per minute to produce a crystalline silicon carbide powder. The crystalline silicon carbide powder thus prepared was heat-treated at 600 ° C. for 6 hours in an air atmosphere to remove unreacted carbon to obtain a high-purity vanadium-containing silicon carbide powder.

The formation of silicon carbide was confirmed by X-ray diffractometer, and it was confirmed that all the peaks match with the silicon carbide peak (FIG. 3). In the case of silicon carbide, X-ray diffraction peaks were clearly observed at positions 35.7, 41.4, and 60 °, indicating that the particles were formed in the β phase (JCPDS No. 74-2307). The shape of the particles was confirmed by a scanning electron microscope and the hexagonal crystals were found to be excellent single phase (FIG. 4). The chemical composition of the silicon carbide powder was found to be 4.90 wt% based on the Korean Industrial Standard (KS L1612). It was confirmed that the crystal phase of silicon carbide did not change even after the decarburization process.

Comparative Example 1

10 g of the vanadium-containing silica precursor synthesized in Preparation Example 3 was uniformly mixed with 4 g of carbon powder through a ball milling process, heated to 1400 ° C at a rate of temperature rise of 20 ° C per minute under an argon atmosphere, and maintained for 5 hours to prepare a silicon carbide powder And then heat-treated at 1800 ° C for 2 hours at a heating rate of 10 ° C per minute to produce a crystalline silicon carbide powder. The crystalline silicon carbide powder thus prepared was heat-treated at 600 ° C. for 6 hours in an air atmosphere to remove unreacted carbon to obtain silicon carbide powder.

The formation of silicon carbide was confirmed by using an X-ray diffractometer. As a result, the X-ray diffraction peak appeared at 35.7, 41.4 and 60 ° in the case of silicon carbide, No. 74-2307).

However, it was confirmed by X-ray diffraction analysis of the grown particles that a new peak corresponding to vanadium carabide (JCPDS No. 73-0476) appeared at positions of 37.2 ° and 43.7 ° (FIG. 5). The morphology of the particles was confirmed by scanning electron microscopy and found to be a mixed phase consisting of hexagonal crystals and small powders (Fig. 6). The chemical composition of the silicon carbide powder was found to be 9.95 wt% based on the purity analysis according to Korean Industrial Standard (KS L1612). This result indicates that vanadium which has not been substituted in the silicon carbide lattice reacts with carbon at high temperature to form vanadium carbide. As a result, the vanadium solubility limit of the vanadium-containing silicon carbide powder of the present invention is 5% The amount of vanadium exceeding the amount that can be contained in the silicon carbide lattice can not be substituted in the lattice, and the crystal quality may be deteriorated when the silicon carbide powder is produced.

Claims (11)

(a) preparing a vanadium-containing silica powder by sol-gel reaction of a reaction mixture represented by the following formula (1);
(b) mixing the vanadium-containing silica powder and carbon to produce a silicon carbide precursor; And
(c) subjecting the silicon carbide precursor thus prepared to heat treatment at a temperature of 1400-2200 DEG C in a vacuum or under a gas atmosphere selected from helium, neon, and argon; and
[Chemical Formula 1]

In the above formula (1)
R is an alkyl group having 5 to 20 carbon atoms or a phenyl group. The method according to claim 1,
The reaction mixture of Formula 1 is synthesized by mixing a silica starting material and a vanadium starting material,
Wherein the silica starting material is at least one selected from silicon alkoxide, siloxane-based polymer, and silsesquioxane-based polymer,
Wherein the vanadium starting material is at least one selected from the group consisting of vanadium alkoxide, vanadium acetylacetonate, and vanadium oxychloride. The method according to claim 1,
Wherein the vanadium content of the vanadium-containing silica powder is 1-5 wt%. The method according to claim 1,
Wherein the silicon carbide precursor is prepared by further mixing at least one selected from the group consisting of carbon black, graphite, pitch, phenolic resin and polystyrene resin in the step (b). The method according to claim 1,
The heat treatment step (c) may include: a first heat treatment step of carbonizing the silicon carbide precursor at 1400 to 1600 ° C; And a second heat treatment step of inducing crystallization at 1800-1900 ° C after the first heat treatment. 6. The method of claim 5,
Wherein the first heat treatment step starts a carbonation reduction reaction at 1400-1600 ° C and is maintained for 5-7 hours. 6. The method of claim 5,
Wherein the second heat treatment step induces crystallization at 1800-1900 ° C for 2-3 hours to obtain a highly crystalline silicon carbide powder. The method according to claim 1,
And calcining the silicon carbide precursor produced in step (b) before the step (c) in a vacuum or a gas atmosphere selected from helium, neon and argon to 600-1000 ° C. Containing silicon carbide powder. The method according to claim 1,
And performing a decarburization process at 600-1000 ° C. in an atmospheric environment after the step (c). The method of manufacturing a vanadium-containing silicon carbide powder according to claim 1, 9. A vanadium-containing silicon carbide powder produced according to any one of claims 1 to 8, wherein the silicon carbide has a purity of 99.0-99.9% of a beta phase crystal, and the average particle size of the vanadium-containing silicon carbide powder is 1- Wherein the vanadium-containing silicon carbide powder is 100 占 퐉. delete

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